JP05-044437A published by the Japanese Patent Office in 1993 discloses a regeneration mechanism for a diesel particulate filter which traps particulate matter discharged by a diesel engine. The filter is installed in the exhaust passage of the engine. When particulate matter accumulates in the filter, the temperature of the filter is raised to burn the particulate matter by raising the exhaust gas temperature, and the particulate matter is thereby removed from the filter.